Crews started on Friday to tear down a building that was the scene of a US school shooting in 2018 that left 17 people dead.
In February that year, Nikolas Cruz, 19, opened fire inside the Parkland, Florida high school from which he had been expelled for disciplinary reasons.
It was one of the deadliest school shootings in US history. Fourteen of those killed were students and the rest were staff.
Cruz is serving a life sentence in prison.
On Friday, a giant excavator started punching holes in the building as it began demolishing it, TV footage showed.
The razing should take some weeks, the Broward County school district said.
Relatives of people who died in the massacre can observe the demolition from an area set aside for them, it said in a statement.
"This is one more step in our healing process," Lori Alhadeff, whose 14-year-old daughter Alyssa was killed at the school, told CNN.
Since the day of the shooting the building has remained as it was -- with bullet holes and bloodstains -- as a crime scene as the murder case proceeded in court.
The demolition was supposed to have started Thursday but was delayed because of torrential rains.